1. Field of Invention
The present invention relates generally to sealing devices and, more particularly, to seals, packings and the like used in environments wherein at least a portion of the sealing device is subjected to extrusion forces. Typically, such forces are experienced by down hole oil tools. For example, in the application of a down hole packer, the area between the oil tool and the well casing is sealed.
2. Related Art
Sealing devices, such as seals or packings, whether of the dynamic or static type, are typically made of materials which, to some extent are resilient or at least deformable. In order to seal effectively, it may typically be necessary for the sealing device to be placed under some compressive loading between the components of the assembly to be sealed. Because of the compressive load and the deformable nature of at least a portion of the seal, if the seal is subjected to sufficient pressure and temperature, there may be a tendency for portions of the seal to be subjected to extrusion forces which may distort the seal and impair its effectiveness as a seal. In more severe cases, such forces may also force portions of the seal into clearances between the components to be sealed.
Previous solutions have been contemplated to prevent or minimize such extrusion problems. For example, FIG. 2 shows a prior seal assembly, or seal array, 200, including a seal body 110 and a pair of non-extrusion end rings 230. Traditional non-extrusion end rings 230 of this type are of one-piece design and are typically constructed of stainless steel wire mesh woven and compacted to provide for controlled deformation while preventing or minimizing extrusion within the annulus formed between the packer assembly 10 and the casing 30 desired to be sealed. A problem with this type of seal array arises as the portion of the non-extrusion end rings 230 proximate the packer assembly 10 may tend to lift outwardly away from the packer assembly 10 as compressive forces are applied to energize the seal body 110 as the portion of the non-extrusion end rings 230 proximate the casing 30 deform radially outward and away from the seal body to fill the annulus 40 therebetween. To minimize the portion of the end rings 230 proximate the mandrel, or body, 50 from lifting away from the packer mandrel 50, other prior seal arrays such as seal array 300 shown in FIG. 3 have provided a notch 330 integrated within the end ring 320. The notch 330 provides a pivot point to control the location of the pivot and to minimize lifting of the end ring 320 from the packer mandrel 50. Such an arrangement has not proven to be sufficient to prevent or adequately minimize extrusion by the seal body 110, particularly between the end ring 320 and the packer mandrel 50. Other prior seal arrays have provided complex arrangements of wedges or other configurations, which also have proven impractical or insufficient.
Accordingly, there is a need for a packer assembly and, more particularly, a seal assembly having a simple, inexpensive, non-extrusion end ring that will minimize lifting of the end ring from the packer mandrel and minimize or prevent extrusion of the seal body within the annulus provided between the packer assembly and the casing, between the element and the mandrel, and between the end ring itself and the packer assembly.
In one aspect, the present invention is directed to a non-extrusion end ring for use with a packer seal array to seal against the inside wall of a well casing and against a packer mandrel, wherein the non-extrusion ring includes at least first and second discrete deformable portions. A feature of this aspect of the invention is that the first discrete deformable portion may be an axial sealing portion for preventing extrusion of a resilient seal body between a packer mandrel and a packer gauge ring, and the second discrete deformable portion may be a radial sealing portion for preventing extrusion of the resilient seal body between the gauge ring and the inside wall of the casing. Another feature is that the axial sealing portion may be adapted to move generally axially along the packer mandrel. The radial sealing portion may also be adapted to move generally radially away from the packer mandrel and generally outwardly away from the seal body to seal an annulus between the packer gauge ring and the inside wall of the well casing. Yet another feature is that the non-extrusion end ring may further include a resilient, deformable, hinge portion disposed between the axial and radial sealing portions.
Still another feature is that the resilient, deformable, hinge portion may be fixedly connected to or integral with the seal body, and the resilient, deformable, hinge portion may be fixedly connected to the axial and radial sealing portions of the non-extrusion end ring. Further, the axial sealing portion may be disposed between the packer mandrel and the radial sealing portion, and the non-extrusion end ring may include a retaining ring associated therewith and located proximate the packer mandrel and the axial sealing portion of the non-extrusion end ring. Still further, the axial and radial sealing portions may each comprise wire mesh, and the wire mesh of the axial sealing portion may be encapsulated within a resilient coating. The resilient coating of the axial sealing portion may be rubber, and the wire mesh of the radial sealing portion may be encapsulated within a resilient coating. Further, the resilient coating of the radial sealing portion may also be rubber. As an alternative to providing a resilient coating, the wire mesh may be impregnated with a resilient material.
Yet another feature of this aspect of the invention is that the wire mesh of both the axial and radial sealing portions may each be separately encapsulated within a resilient coating, and the resilient coating may be rubber. Further, the wire mesh of both the axial and radial sealing portions may be encapsulated together within a resilient coating, and the resilient coating may be rubber.
In another aspect, the present invention is directed to a seal array for use with a packer having a packer mandrel and first and second gauge rings for compressing and energizing the seal array to seal against the inside wall of a well casing and against the packer mandrel, comprising: a resilient seal body; at least a first and second non-extrusion end ring disposed proximate opposing ends of the seal body between the seal body and the first and second gauge rings, respectively; and each of the non-extrusion rings including at least first and second discrete deformable portions.
A feature of this aspect of the present invention is that the first discrete deformable portion may be an axial sealing portion for preventing extrusion of the seal body between the packer mandrel and a packer gauge ring, and wherein the second discrete deformable portion is a radial sealing portion for preventing extrusion of the resilient seal body between the gauge ring and the inside wall of the casing. The axial sealing portion may be adapted to move generally axially along the packer mandrel, and the radial sealing portion may be adapted to move generally radially away from the packer mandrel and generally outwardly away from the seal body to seal an annulus between a packer gauge ring and the inside wall of the well casing. The seal array may further include a resilient, deformable, hinge portion disposed between the axial and radial sealing portions, and the resilient, deformable, hinge portion is fixedly connected to or integral with the seal body. The resilient, deformable, hinge portion may be fixedly connected to the axial and radial sealing portions of the non-extrusion end ring, and the axial sealing portion may be disposed between the packer mandrel and the radial sealing portion.
Another feature of this aspect of the invention is that the seal body may include a retaining ring associated therewith and located proximate the packer mandrel and the axial sealing portion of the non-extrusion end ring. Further, the axial and radial sealing portions may each comprise wire mesh, and the wire mesh of the axial sealing portion may be encapsulated within a resilient coating. The resilient coating of the axial sealing portion may be rubber, and the wire mesh of the radial sealing portion may be encapsulated within a resilient coating. The resilient coating of the radial sealing portion may be rubber, and the wire mesh of both the axial and radial sealing portions may each be separately encapsulated within a resilient coating, which may be rubber. Further, the wire mesh of both the axial and radial sealing portions may be encapsulated together within a resilient coating, and the resilient coating may be rubber.
In still another aspect, the invention may be directed to a packer assembly to seal against the inside wall of a well casing, comprising: a packer mandrel; a seal array disposed around the packer mandrel, including: a resilient seal body; at least a first and second non-extrusion end ring disposed proximate opposing ends of the seal body; each of the non-extrusion rings including at least first and second discrete deformable portions; and first and second gauge rings disposed around the packer mandrel on opposing ends of the seal array for compressing and energizing the seal array to seal against the inside wall of a well casing and against the packer mandrel. A feature of this aspect of the invention is that the first discrete deformable portion may be an axial sealing portion for preventing extrusion of the seal body between the packer mandrel and a packer gauge ring, and the second discrete deformable portion may be a radial sealing portion for preventing extrusion of the resilient seal body between the gauge ring and the inside wall of the casing.
Another feature of this aspect of the invention is that the axial sealing portion may be adapted to move generally axially along the packer mandrel, and the radial sealing portion may be adapted to move generally radially away from the packer mandrel and generally outwardly away from the seal body to seal an annulus between a packer gauge ring and the inside wall of the well casing. The packer assembly may further include a resilient, deformable, hinge portion disposed between the axial and radial sealing portions, and the resilient, deformable, hinge portion may be fixedly connected to or integral with the seal body, wherein the resilient, deformable, hinge portion may be fixedly connected to the axial and radial sealing portions of the non-extrusion end ring. The axial sealing portion may be disposed between the packer mandrel and the radial sealing portion.
Still another feature of this aspect of the invention is that the seal body may include a retaining ring associated therewith and located proximate the packer mandrel and the axial sealing portion of the non-extrusion end ring. Further, the axial and radial sealing portions may each comprise wire mesh, and the wire mesh of the axial sealing portion may be encapsulated within a resilient coating, wherein the resilient coating of the axial sealing portion may be rubber. Further, the wire mesh of the radial sealing portion may be encapsulated within a resilient coating, which may be rubber. Still further, the wire mesh of both the axial and radial sealing portions may each be separately encapsulated within a resilient coating, which may be rubber. Still further, the wire mesh of both the axial and radial sealing portions may be encapsulated together within a resilient coating, and the resilient coating may be rubber.